Locking device for a vacuum tube distribution system



Sept. 28, 1965 L. F. APEL 3,

LOCKING DEVICE FOR A VACUUM TUBE DISTRIBUTION SYSTEM Filed Sept. 27,1963 INVENTOR.

L 0 0/5 F A PEIL ATT Q/wsy United States Patent 3,208,691 LOCKING DEVICEFOR A VACUUM TUBE DISTRIBUTION SYSTEM Louis F. Apel, 648 Atalanta,Webster Groves, Mo. Filed Sept. 27, 1963, Ser. No. 312,268 3 Claims.(Cl. 24'328) (Granted under Title 35, US. Code (1952), see. 266) Theinvention described herein may be manufactured and used by or for theGovernment for governmental purposes without the payment to me of anyroyalty thereon.

The present invention relates to the field of pneumatic tube systems andmore particularly to locking devices for individually locking theterminal doors of a vacuum type, pneumatic tube distribution system.

The terminals of many vacuum tube distribution systems are furnishedwith doors which can be opened regardless of whether or not the systemis shut down, thus it is possible to insert a carrier into the systemwhen the vacuum within the system is inadequate to propel the carrier.This may occur for example when the vacuum pump is shut down or is notoperating properly.

Accordingly, an object of this invention is to provide individuallocking devices for the terminal doors of a vacuum tube distributionsystem responsive to the pressure within said system which prevents theopening of the terminal doors of said system when an inadequate vacuumexists therein.

The precise nature of the invention, its other objects and advantagesare fully explained in the description which follows and in thedrawings.

FIG. 1 is a perspective view showing the locking device installed in theterminal of a vacuum tube distribution system;

FIG. 2 is an exploded view showing the components of the preferred formof the locking mechanism;

FIG. 3 shows a latch plate which, together with the locking mechanism ofFIG. 2 comprises the locking device; and

FIG. 4 is a sectional view of the locking mechanism taken along line 3-3of FIG. 1.

FIG. 1 shows a terminal through which a tubular shaped carrier may beinserted into a vacuum tube distribution system. The carrier isthereafter propelled by differential air pressure to another terminal.The terminal shown in FIG. 1 comprises a terminal door frame 1 installedin building wall 2. Terminal door 3 is hingedly attached to wall 2 byspring loaded hinge 4. The spring of hinge 4 maintains terminal door 3in a normally closed position. Terminal door 3 may be opened by handle 5when it is desired to insert a carrier into the distribution system. Airseal strip 6 made of suitable resilient material surrounds the doorframe and prevents the leakage of air into the system when door 3 isshut.

The locking device of the present invention comprises a lock mechanism 7and latch plate 8. The lock mechanism is preferably installed on theinside of terminal door 3 at a point near the bottom and near theoutside edge of the terminal door. Latch plate 8 is installed on thebottom floor of the terminal door frame at a location which is beneathlock mechanism 7 when the terminal door is closed.

Lock mechanism 7 comprises a lock body 7a consisting of a cap 9, acentral portion 10 and a base 11. A circular, vertical bore 12 isprovided in central portion 10. The upper portion 12a of this bore iscylindrical while the lower portion 12b is tapered. Circular plunger 13is slidably received in the cylindrical portion 12a of vertical bore 12.Downward travel of plunger 13 is limited by the lower tapered zone 12bof vertical bore 12. Lock bolt 14 is attached tothe center of circularplunger 13 and depends therefrom. Circular holes 15 and 16 are providedin cap 9 and base 11 respectively of the lock body. Cap hole 15 issomewhat smaller than circular plunger 13; when the lock body isassembled the cap hole permits air to escape from above the plunger.Base hole 16 is sized to accommodate lock bolt 14 and is alignedtherewith. When lock mechanism 7 is assembled and operating lock bolt 14alternatively projects downward through the base hole 16 or is withdrawnfurther into the lock body.

Cap 9, central portion 10 and base 11 of the lock body have fiatportions 9a, 10a and 11a, respectively, which form a single flat surface7b when the lock body is assembled. The three elements of lock body 7aand plunger 13 may be made of any suitable material such as Plexiglas.The lock bolt may be made of steel rod adapted to be screwed into athreaded hole provided in the plunger. If made of Plexiglas thecomponents of lock body 7a may be cemented together after the plungerand lock bolt are inserted in vertical bore 12. Flat surface 7b of thelock body may then be cemented to the inside surface of terminal door 3or the lock body may be attached to the terminal door by any suitablemeans. Generally rectangular latch plate 8 comprises an inclined cammingsurface 8a, a vertical ledge 8b and a hole sized and located toaccommodate lock bolt 14 when the terminal door is closed and locked.

A circular passage 17 is drilled through terminal door 3 in alignmentwith circular passage 18 in the lock body; passage 18 opens in to thetapered portion 12b of vertical bore 12. Thus air at atmosphericpressure is always present in the tapered portion of the vertical boreand at the lower face of plunger 13.

The operation of the locking device will now be explained. When terminaldoor 3 is closed and an operat ing vacuum exists within the distributionsystem the top surface of plunger 13 is exposed through cap hole 15 tothe reduced pressure of the system, while the lower surface of theplunger is exposed to atmospheric pressure through passages 17 and 18.The plunger therefore remains near the top of vertical bore 12; lockbolt 14 does not engage latch plate 8 and the door may be opened orclosed at will. When on the other hand an operating vacuum does notexist in the system both the top and bottom surfaces of plunger 13 areexposed to atmospheric pressure. The plunger falls through the taperedportion 12b of vertical bore 12 and lock bolt 14 engages latch plate 8.

It will be apparent that a number of changes may be made in the lockingdevice without departing from the spirit of the present invention. Forexample, latch plate 8 may be made without the lock bolt receiving hole80 or it may be replaced by other suitable bolt engaging means which maybe integral with the terminal door frame or which may be fabricatedseparately and attached thereto. Also lock body 7a need not be made inthree parts as in the embodiment described above.

I claim:

1. A locking device to secure the terminal door of a vacuum tubedistribution system when an operating vacuum does not exist within thesystem comprising:

a. a lock body aflixed to the inside surface of the terminal door;

b. a lock bolt slidably received in said lock body;

c. lock bolt engaging means afiixed within the terminal to the bottom ofthe door frame; and

d. means within said lock body responsive, when the terminal door isclosed, to a change in the pressure differential between inside andoutside of said terminal to selectively lower and raise said lock boltinto and out of engagement with said bolt engaging means.

2. A locking device to secure the terminal door of a 3 4 vacuum tubedistribution system when an operating vacu- V 3. The locking devicedescribed in claim 2 wherein: um does not exist within the systemcomprising: a. the lock body comprises a cap member, a central a. a lockbody, afiixed to the inside surface of the portion having a verticalcircular bore therethrough terminal door, having a vertical bore formedtheresaid bore including a lower tapered zone, and a base in; 5 portionhaving a vertical bore adapted to slidably reb. a plunger slidablyreceived within said vertical bore; ceive said lock bolt; and c. lockbolt engaging means affixed within the terminal b. the lock boltengaging means comprises a latch to the bottom of the door frame; platehaving a camming surface, a vertical ledge, and d. a lock bolt dependingfrom said plunger and adapted a hole adapted to receive said lock bolt.to move therewith downward to a position in which 10 it engages saidlock bolt engaging means and upward References Clted by the Exammel' toa position in which it is withdrawn from said lock UNITED STATES PATENTSbolt engaging means; e. passages formed in the terminal door and in said2242707 5/41 Haynes 292 144 lock body adapted to expose the bottom ofsaid plung- 15 AMUEL F COLEMAN Primary Examiner er to atmosphericpressure; and f. an opening in said lock body adapted, when the ter-ANDRES NIELSEN, Examinerminal door is closed, to expose the top of saidplunger to the pressure within the terminal.

1. A LOCKING DEVICE TO SECURE THE TERMINAL DOOR OF A VACUUM TUBEDISTRIBUTION SYSTEM WHEN AN OPERATING VACUUM DOES NOT EXIST WITHIN THESYSTEM COMPRISING: A. A LOCK BODY AFFIXED TO THE INSIDE SURFACE OF THETERMINAL DOOR; B. A LOCK BOLT SLIDABLY RECEIVED IN SAID LOCK BODY: C.LOCK BOLT ENGAGING MEANS AFFIXED WITHIN THE TERMINAL TO THE BOTTOM OFTHE DOOR FRAME; AND D. MEANS WITHIN SAID LOCK BODY RESPONSIVE, WHEN THETERMINAL DOOR IS CLOSED, TO A CHANGE IN THE PRESSURE DIFFERENTIALBETWEEN INSIDE AND OUTSIDE OF SAID TERMINAL TO SELECTIVELY LOWER ANDRAISE SAID LOCK BOLT INTO AND OUT OF ENGAGEMENT WITH SAID BOLT ENGAGINGMEANS.